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A209953
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Number of (n+1) X 2 0..2 arrays with every 2 X 2 subblock having one, three or four distinct clockwise edge differences.
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1
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71, 567, 4521, 36057, 287559, 2293335, 18289737, 145863801, 1163288871, 9277428663, 73989087849, 590075690265, 4705955031303, 37530800068887, 299314580024457, 2387085211367865, 19037414768987367, 151826654264588919
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 6*a(n-1) + 15*a(n-2) + 6*a(n-3).
Empirical g.f.: x*(71 + 141*x + 54*x^2) / (1 - 6*x - 15*x^2 - 6*x^3). - Colin Barker, Jul 14 2018
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EXAMPLE
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Some solutions for n=4:
..1..1....0..2....0..1....2..1....2..1....2..1....1..2....1..2....1..2....2..1
..0..0....2..1....2..0....0..2....0..2....0..0....0..2....1..1....0..2....2..2
..2..0....0..1....1..2....1..1....2..1....1..1....2..1....1..1....0..2....1..2
..0..0....0..1....2..0....1..2....0..2....1..0....2..0....1..0....2..2....0..2
..0..0....1..1....0..1....1..1....1..0....2..2....0..1....1..2....0..2....2..2
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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